Pawl latch assemblies



Feb. 27, 1962 M. c. PLUYLAAR 3,023,041

PAWL LATCH ASSEMBLIES Filed Aug. 29, 1960 JNVENTOR. MAE/7N c. Ply/(A1412 wiaw Unite States Airplane Company, Seattle, Wash, a corporation of Delaware Filed Aug. 29, 1960, Ser. No. 52,722 4 Claims. (Cl. 292-212) The present invention relates to doors of the nature of cowl panels in aircraft, which must be dependably returned to locked position after each opening and which should be held by some resistance in unlocked position, and specifically to the latch or lock to hold the door closed.

Such cowl panel locks, or latching devices, are usually constructed so that exteriorly they are flush with the skin of the door or the fixed cowl panel (on whichever thereof the lock is mounted), and the entire locking mechanism is on the blind side of the same, i.e. interiorly disposed, and cannot be examined after locking to determine visually if it is in the locked or the unlocked position. Dependence heretofore has had to be placed on the care with which the mechanic who locks the device makes sure, by viewing it before the door is closed, that when the cowl latch is turned through a given angle to its locked position it is in fact in that position. Since there are numerous such latches to refasten, which may be in various positions, or wholly released, and since each incorporates a screw as a pivot, and this screw must be screwed tight to prevent its loss from vibration or the like, it is not always possible for the mechanic dependably to assure himself that he has turned the locking bars all to the locked position. He will screw the screw home, and then is not sure that in doing so he has not turned the locking bar past its locked position, or failed to turn it fully to the locked position.

Attempts have been made to provide indicating devices for such cowl panel latches, but heretofore without success. It is the purpose of the present invention to provide a successfully and dependably operable indicating device for association with such a cowl panel latch that will indicate visually from the exterior the locked or unlocked position or any intermediate position of the locking bar of the latch. It is a further object to provide a device of the character just indicated which in itself can lie substantially flush with the surface of the door on which it is mounted, and which is simple in construction and of light weight.

With these objects in mind, and others as will appear more fully hereinafter, this invention comprises the novel door latch position indicator and its relationship to the door panel latch and to the parts held together by such latch, all as shown in the accompanying drawings and as will be more fully indicated in this specification, and the particular novel features whereof will be pointed out in the claims at the end of this specification.

In the accompanying drawings the invention is shown embodied in a form such as is presently preferred by FIGURE 1 is an isometric view from the interior illustrating the latch mounted upon the door, in fully locked position with relation to the edge of the fixed nacelle.

FIGURE 2 is an interior elevational view illustrating the latch in full lines in the locked position and in dotdash lines in the unlocked position.

FIGURE 3 is an exterior elevation showing the indicator device in position to indicate that the latch is fully locked, and FIGURE 4 is a similar view with the indicator device showing that the latch is unlocked.

FIGURE 5 is an elevational edge view of the latch tttt mechanism, partly broken away, and with the door and nacelle in section.

For purposes of illustration the latch may be assumed to be mounted upon the door D which afiords access to the interior of a nacelle N of an airplane. This would be the usual mounting, although there is no reason why the latch might not in some instances be mounted along the edge of the nacelle. It is in any event mounted near the edge of the element which supports it, and near enough to the complemental element to engage the latters edge.

It is suitably supported interiorly of the door D, as by an anchor block '2 which is itself riveted or otherwise secured to the door D as indicated by the rivets 26'. Use of the anchor block is not essential, and if used it need be in effect little more than a doubling plate attached to the inside of the door panel D. An elongated locking bar 1 is pivotally mounted upon the anchor block 2 adjacent the edge of the door D to which end the locking bar '1 is formed with an integral central boss 10 the bore whereof is elliptical in shape and threaded interiorly to receive a screw 3, the headed end 30 of which lies flush with the exterior surface of the door D. The elliptical shape locks in place the shank of the screw 3 which passes through an aperture in the door.

According to this invention the aperture that passes the screw is made enough larger to pass an indicator element 4. This indicator device is formed with a head 4%) at its exterior end, larger than the head 30 of the screw 3 and seated within a countersunk recess in the door I),

so that it is, in effect, flush with the surface of the door,

as is the head 30 of the screw. The interior end, or blind end of the indicator element 4 consists of a pair of spaced legs 41 which straddle the central portion of the locking bar 1, so that when the two are thus interengaged, as is best seen in FIGURES 1 and 2, the indicator element 4 will of necessity rotate with rotation of the locking bar 1, and can not rotate relative thereto, although the screw 3 might.

The screw 3 is threaded home as tightly as may be necessary, so tightly in the elliptical bore that rotation of its head 3% will eifect rotation of the locking bar 1 rather than unscrewing of the screw, and through the interconnection of the legs 41 with the locking bar rotation of the screw will also effect rotation of the indicator device 4. To release the lock the mechanic will engage the slot of the screw head 30 with a screwdriver and effect its rotation. The locking bar I, if initially locked in the full line position of FIGURE 2, will rotate to the dot-dash line position thereof, where its rotation will be halted by an upstanding shoulder 22 of the anchor block. In addition, one end of the locking bar will ride upon a rubbing surface 23 upstanding from the anchor block, and the frictional interengagement will tend to hold the locking bar in its unlocked position. Exteriorly the indicating device has grooves 44 formed in the visible portion of its head 49 and these, as shown in FIGURE 4, will align With a fixed indicating mark 6 to indicate that the locking bar I is now in the unlocked position. When the door is to be relocked, after closing it with respect to thenacelle edge, the screwhead 30 is rotated in the opposite sense and interiorly the end of the locking bar 1 rotates until it overlies the edge of the nacelle (as seen in FIGURE 5 for instance or in FIGURE 1), and now the index mark 44 of the head 40 is aligned with the fixed index mark 7, as in FIGURE 3, to indicate that parts are in the locked position. However far the screw head 30 was initially turned to insure its tightness, this has no effect on the indicator, for the indicator cooperates with marks 6 and '7, not with the slot in the screw head. In either position, open or locked, there is a clear visual indication which is unmistakable, and if the locking bar should be stopped in an intermediate position this, too, will be clearly indicated. The shoulder 22 is so positioned as to stop the rotation of the'locking bar 1 in either its locked or its unlocked position, but dependence is not placed on this but rather on the visual indication afforded by the relative positioning of the rotative index mark 44 with relation to the fixed index marks 6 or 7.

I claim as my invention:

1. A blind door fastener device for a door mounted in relation to a door frame, comprising an anchor block supported at the inner side of, and adjacent the edge, of the door, an elongated locking bar having a centrally located, interiorly threaded boss, an indicator element formed with a centrally apertured head at its outer end and with means at its inner end interengageable by relative axial movement with said locking bar for conjoint rotation about the axis of said boss, the door being apertured for passage of said interengaging means, but formed with a rotative seat for said head, and a headed screw passing through the centrally apertured head of the indicator element and into the threaded boss of the locking bar, with its head engaging the head of the indicator element and the interengaging means of the latter operatively engaged with the locking bar, and an index mark carried by and rotative with the head of the indicator element, for cooperation with surrounding fixed index marks, to indicate the locked or unlocked position of the locking bar.

2. A door fastener device as in claim 1, wherein the indicator device at its inner end is formed with spaced legs to straddle the locking bar, for their conjoint rotation, and constituting the interengaging means.

3. A door fastener device as in claim 1, including stop shoulders upstanding from the anchor block in the path of rotation of the locking bar, and located to afford the latter approximately 90 of rotation between its locked and its unlocked positions.

4. A door fastener device as in claim 1, including a rubbing area upstanding from the anchor block, in the path of rotation of the locking bar, as the latter approaches its unlocked position, to frictionally retain the same therein.

References Cited in the file of this patent UNITED STATES PATENTS 

